Sphalerite


Sphalerite
Sphalerite

Sphalerite on dolomite from the Tri-State District, Jasper County, Missouri, USA
General
Category Sulfide mineral
Chemical formula (Zn,Fe)S
Strunz classification 02.CB.05a
Dana classification 02.08.02.01
Identification
Color Brown, yellow, red, green, black.
Crystal habit Euhedral crystals – occurs as well-formed crystals showing good external form. Granular – generally occurs as anhedral to subhedral crystals in matrix.
Crystal system Isometric hextetrahedral (4 3m)
Twinning Simple contact twins or complex lamellar forms, twin axis [111]
Cleavage [110] perfect
Fracture Uneven to conchoidal
Mohs scale hardness 3.5-4
Luster Adamantine, resinous, greasy
Streak brownish white, pale yellow
Diaphaneity Transparent to translucent, opaque when iron-rich
Specific gravity 3.9–4.2
Optical properties Isotropic
Refractive index nα = 2.369
Other characteristics non-radioactive, non-magnetic, fluorescent and triboluminescent.
References [1][2][3]

Sphalerite ((Zn,Fe)S) is a mineral that is the chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron. When iron content is high it is an opaque black variety, marmatite. It is usually found in association with galena, pyrite, and other sulfides along with calcite, dolomite, and fluorite. Miners have also been known to refer to sphalerite as zinc blende and black-jack.

Contents

Chemistry

The crystal structure of sphalerite

         

The mineral crystallizes in the cubic crystal system. In the crystal structure, zinc and sulfur atoms are tetrahedrally coordinated. The structure is closely related to the structure of diamond. The hexagonal analog is known as the wurtzite structure. The lattice constant for zinc sulfide in the zincblende crystal structure is 0.541 nm,[4] calculated from geometry and ionic radii of 0.074 nm (zinc) and 0.184 nm (sulfide). It forms ABCABC layers.

Varieties

Sharp, tetrahedral sphalerite crystals with minor associated chalcopyrite from the Idarado Mine, Telluride, Ouray District, Colorado, USA (size: 2.3×2.3×1.2 cm)

Its color is usually yellow, brown, or gray to gray-black, and it may be shiny or dull. Its luster is adamantine, resinous to submetallic for high iron varieties. It has a yellow or light brown streak, a Mohs hardness of 3.5–4, and a specific gravity of 3.9–4.1. Some specimens have a red iridescence within the gray-black crystals; these are called "ruby sphalerite." The pale yellow and red varieties have very little iron and are translucent. The darker more opaque varieties contain more iron. Some specimens are also fluorescent in ultraviolet light. The refractive index of sphalerite (as measured via sodium light, 589.3 nm) is 2.37. Sphalerite crystallizes in the isometric crystal system and possesses perfect dodecahedral cleavage. Gemmy, pale specimens from Franklin, New Jersey (see Franklin Furnace) are highly fluorescent orange and/or blue under longwave ultraviolet light and are known as cleiophane, an almost pure ZnS variety.

Occurrence

Sphalerite is the major ore of zinc and is found in thousands of locations worldwide.[2]

Sources of high quality crystals include:[3]

Gemstone use

Gemmy, 1.8 cm, twinned, cherry-red sphalerite crystal from Hunan Province, China

Crystals of suitable size and transparency have been fashioned into gemstones, usually featuring the brilliant cut to best display sphalerite's high dispersion of 0.156 (B-G interval)—over three times that of diamond. Freshly cut gems have an adamantine luster. Owing to the softness and fragility the gems are often left unset as collector's or museum pieces (although some have been set into pendants). Gem-quality material is usually a yellowish to honey brown, red to orange, or green.

Another sphalerite sample

See also

References

  1. ^ Sphalerite. Webmineral. Retrieved on 2011-06-20.
  2. ^ a b Sphalerite. Mindat.org. Retrieved on 2011-06-20.
  3. ^ a b Handbook of Mineralogy
  4. ^ International Centre for Diffraction Data reference 04-004-3804 , ICCD reference 04-004-3804.

External links


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Look at other dictionaries:

  • Sphalérite — Catégorie II : sulfures et sulfosels[1] Sphalérite, Mines de Huaron Pérou (4x4cm) …   Wikipédia en Français

  • Sphalerite — Sphalérite Sphalérite Catégorie II : sulfures et sulfosels Sphalérite, Mines de Huaron Pérou (4x4cm) …   Wikipédia en Français

  • sphalérite — ● sphalérite nom féminin (grec sphaleros, trompeur) Synonyme de blende. ● sphalérite (synonymes) nom féminin (grec sphaleros, trompeur) Synonymes : blende …   Encyclopédie Universelle

  • Sphalerite — Sphal er*ite, n. [Gr. ??? slippery, uncertain. See {Blende}.] (Min.) Zinc sulphide; called also {blende}, {black jack}, {false galena}, etc. See {Blende} (a) . [1913 Webster] …   The Collaborative International Dictionary of English

  • Sphalerite — Sphalerite, Mineraliengruppe, soviel wie Blenden …   Meyers Großes Konversations-Lexikon

  • sphalerite — [sfal′ər īt΄, sfāl′ər īt΄] n. [Ger sphalerit < Gr sphaleros, deceptive (< sphallein, to trip, deceive: for IE base see SPOIL) + it, ITE1: so named from being mistaken for other ores] a usually brownish mineral, (Zn,Fe)S, the chief ore of… …   English World dictionary

  • sphalerite — /sfal euh ruyt , sfay leuh /, n. a very common mineral, zinc sulfide, ZnS, usually containing some iron and a little cadmium, occurring in yellow, brown, or black crystals or cleavable masses with resinous luster: the principal ore of zinc and… …   Universalium

  • sphalerite — Blende Blende, n. [G., fr. blenden to blind, dazzle, deceive, fr. blind blind. So called either in allusion to its dazzling luster; or (Dana) because, though often resembling galena, it yields no lead. Cf. {Sphalerite}.] (Min.) (a) A mineral,… …   The Collaborative International Dictionary of English

  • sphalerite — sfaleritas statusas T sritis radioelektronika atitikmenys: angl. sphalerite vok. Sphalerit, m; Zinkblende, f rus. сфалерит, m; цинковая обманка, f pranc. blende, f; sulfure de zinc, m …   Radioelektronikos terminų žodynas

  • sphalerite — sfaleritas statusas T sritis chemija apibrėžtis Mineralas. formulė ZnS atitikmenys: angl. sphalerite rus. сфалерит; цинковая обманка ryšiai: sinonimas – cinko blizgis …   Chemijos terminų aiškinamasis žodynas


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